

ABSTRACT

A heater comprises a substrate (1) having an electrically-insulative ceramic coating (2) and a heater track (3) deposited on the coating (2) and electrically connected to a power supply via ends (4, 5). The heater track (3) consists of a composite material having predetermined proportions of a metal and a material capable of undergoing a reversible change in volume at a predetermined phase transition temperature. The change in volume changes the proportions of metal to material and thus changes the resistivity of the composite material, so that the heater can be used as a self-regulating thermal cut-out device by limiting its own heat output to the phase transition temperature.



